SK280652B6 - Ready-mixed cementitious composition - Google Patents

Abstract

A cementitious composition contains calcium sulfate hemihydrate as a filler material and non-calciun bearing phosphate additives as a set retarder, bonding agent and water. The composition can be utilised for finishing seams between gypsum drywall panels, firestop compounds, ornamental and casting plasters, spackling compounds, and basecoat and finishing plasters.

Description

Technical field

The invention relates to a cementitious composition which is relatively stable in a premixed state (i.e., premixed with water) and which can solidify and harden upon introduction of the accelerator into the composition. The ready-to-use cementitious cementitious compositions of the invention are useful in a variety of applications, including but not limited to, but not limited to, any jointing compositions for finishing joints between gypsum panels of drywall, fire protection, decorative and cast plaster, grout and base coatings and finishing plasters ). If the finished cement mixture is prepared as a joint compound, it can also be used as a drying compound without the addition of an accelerator.

BACKGROUND OF THE INVENTION

The walls formed by the gypsum panels are usually constructed in such a way that the wall panels are fixed to the pins and the joints between the panels are filled and coated with specially prepared mixtures called jointing mixtures. The moistened taping grate is placed inside the joint formed by the accessed edges of the wall panels and a paper reinforcing strip is placed in the joint along with the joint compound, which is then allowed to dry. When the joint compound is dry, apply the joint compound (topping grease) to the joint and allow it to dry. Thereafter, the joint compound can be easily sandblasted and the wall can optionally be finished with a decorative coating (paint, texture or wallpaper) or if the joint needs to be covered, a third joint compound can be applied and after drying it can be easily sanded and a decorative coating applied to the wall. . Instead of using two kinds of bonding compounds, a multipurpose bonding compound is commercially available, which is used both for laying the strip and for the final coating or coatings. If a glass fiber reinforcing strip is used, it is applied to the wall before applying the jointing compound. The bonding mixture is applied to the glass fiber reinforcing strip and is forced to penetrate the reinforcing strip.

Typically, the binding compositions comprise a filler, a binder and a hardener. Taping grades generally contain more binder than topping grades. Common binders are calcium carbonate, dehydrated calcium sulfate (gypsum) and calcium sulfate hemihydrate (Paris plaster). Calcium sulphate hemihydrate is used only in the jointing compositions of U.S. Patent No. 3,297,601. However, in general construction practice, it is generally preferred to use ready-to-wet pre-wetting drying joints containing either calcium carbonate or gypsum as a filler.

Conventional drying compositions of the drying type encounter a shrinkage problem which makes it difficult to obtain a smooth wall surface. The shrinkage of prior art bonding compositions can be particularly unpleasant when the second layer is applied to the not completely dried earlier layer. The areas coated or filled with the incompletely dried binding compound subsequently shrink, which can only occur when the wall is finished and decorated. In some cases where delayed shrinkage is excessive, workers are required to return to the work site for re-finishing and decorating.

First, there was an essential need in the fastener industry to prepare a fastener that solidifies or hardens rapidly, reducing the time required to expose the flat panel dry wall sets and less shrinking. Binder compositions of this type would be a significant advance in the art and would substantially reduce the cost and time required to finish and decorate wall surfaces.

To cope with the drawbacks of the drying type bonding compositions, solidifying type powder bonding compositions have been developed. In solidifying type fasteners, the main filler is calcium sulfate hemihydrate (calcined gypsum). The powder mixture is mixed dry and mixed with water when ready for use. The water reacts with calcium sulfate hemihydrate to form gypsum (calcium sulfate dihydrate). In this mixture, the setting time is considerably shorter than the time required to dry the drying type binder. However, the solidification-type jointing compositions have the disadvantage that they cannot be prepared as ready-to-use, ready-to-use jointing compositions, since they have a short useful life after mixing with water and cannot be stored in a moistened state.

The prior art is characterized, for example, by U.S. Pat. No. 4,661,161, which relates to a ready-mixed, curing type binder. This document discloses a two-component mixture, with a premixed cementitious component comprising moistened calcium sulfate hemihydrate, conventional binders and thickeners, and a combination of solidification retardants formed by animal tissues and a chelating agent for calcium ion chelation. The second component is an accelerator which produces a compound with a higher log K value than calcium, such as compounds with ferric ions (e.g. ferric sulfate). It is claimed that the cement mix has a reasonably long shelf life for commercial use. When the two components are mixed, the cement component receives water after a suitable time to form a solidifying material with acceptable bonding properties.

However, it has been shown that the ready-to-bond fasteners of U.S. Pat. No. 4,661,161 cannot be expanded commercially due to storage problems of the pre-mixed cement component. It has been found that the setting retard mixture in the pre-mixed cement component degrades by aging, causing the cement component to solidify in the packages without the addition of an accelerator. In addition, when the premixed cement component ages in the warehouse, the solidification time of the system is significantly reduced and becomes uncontrollable and unpredictable.

It is an object of the present invention to provide a ready-mixed, solidified-type blend with a shelf life of at least about several months.

It is a further object of the present invention to provide a ready mixed mix of solidifying type for filling and sealing joints between adjacent wall panels, wherein the jointing composition has a relatively short solidification time after activation by the accelerator.

Yet another object of the present invention is to provide a ready mixed cementitious composition for use as either a solidification type mixture when mixed with an accelerator or as a drying type mixture without the addition of an accelerator.

SUMMARY OF THE INVENTION

The finished cement composition according to the invention consists in that it contains calcium sulphate hemihydrate as a filler and calcium-free phosphate as a retardant and water. The composition additionally comprises calcium carbonate, a binder and a thickener.

The present invention relates to a cementitious composition of the solidifying type which can be brought to a ready state (premixed with water) and which can be solidified or hardened by reproducing the accelerator by the introduction and with the possibility of predicting solidification time. It has been found that a cementitious composition comprising calcium sulfate hemihydrate as the main filler material can be premixed with water and some calcium-free phosphate additive to prevent solidification in the presence of water. An accelerator may be added to the ready-mixed cement base to initiate solidification, or the ready-mixed composition may be used as a drying type mixture without the addition of an accelerator.

Further features and advantages of the premixed cementitious compositions of the invention will be apparent from the description of suitable embodiments.

The developed mixture has excellent shelf life in ready-mixed state (pre-mixed with water) after introduction of a special retarder into the ready-mixed mixture. The decisive ingredient in the cementitious composition is a long-term retardant, which keeps the ready mixed cement base in a non-solidifying state, the presence of water would normally cause the calcium sulfate hemihydrate filler to solidify. The inventive additives which provide long-term retardation in ready-mixed cement mixtures are calcium-free phosphates. In particular, it has been found that (1) zinc hexametaphosphonate and (2) potassium tripolyphosphate provide a long-term delaying effect, whereas (3) tetranatrium pyrophosphate provides the longest lasting long-term solidification retarding effect. Other effective solidifying retardants include (4) sodium tripolyphosphate, (5) monoammonium phosphate, and (6) monobasic potassium phosphate.

Generally, the retarding effect on solidification is provided by a small amount of phosphate additive in an amount of about 0.1 to about 10% by weight based on the weight of the total dewatered mixture. In addition to calcium sulfate hemihydrate, the filler may also include calcium carbonate.

As mentioned, the main component in the cementitious masterbatch is calcium sulfate hemihydrate as a filler. This component allows the mixture to function as a solidification type mixture. It has been found that an a-crystalline form of calcium sulfate hemihydrate has been found to be useful for long-term maintenance of the non-cured ready-mixed calcium phosphate-free blend. Generally, calcium sulfate hemihydrate is at least about 20% by weight of the unwetted cementitious base composition and may amount to about 99% by weight. In addition, calcium carbonate may also be included as a filler. The calcium carbonate may be up to about 75% by weight of the non-wetted cementitious base composition.

In the preparation of the cementitious base composition as a joint compound, conventional joint additives may be incorporated into the compound. The latex emulsion binder is a significant additive, well known to those skilled in the art as a binder. Any latex binder may be used, with emulsions with polyvinyl acetate and ethylene vinyl acetate being preferred. If present, the latex is about 1 to about 15% by weight of the composition prior to the addition of water.

Generally, it is preferred that the cementitious base composition, when used as a binder, contains a small amount of cellulosic thickener. Conventional cellulose thickeners such as ethylhydroxyethylcellulose, hydroxypropylmethylcellulose, methylhydroxypropylcellulose and hydroxyethylcellulose can be used in the binder compositions of the invention. The amount of cellulosic thickener, if present, may be about 0.1 to about 2% by weight of the total ingredients of the composition (without adding water to obtain a ready-mixed composition).

The binder composition of the invention may also comprise a non-leveling agent such as attapulgic clay. This additive provides a misalignment to trap water, which first provided asbestos. Attapulgic clay has been found to provide binding compositions with good processing properties. The amount of non-balancing agent, if present, may be about 1 to about 10% by weight of the composition prior to the addition of water. Other clays, such as sepiolite, bentonite and montmorillonite, may also be incorporated into the binder mixture.

Conventionally ready-mixed jointing compositions often contain mica, talc or sericit to provide crack resistance after drying. These additives can be dispensed with in the jointing compositions according to the invention because they have excellent resistance to cracking without the use of mica or talc; however, it may be desirable to incorporate a small amount of mica or talc in the formulation to provide improved slip and processability. When used in the jointing compositions of the invention, the amount of mica or talc may be about 2 to about 15% by weight of the composition prior to the addition of water.

The ready-mixed binder compositions of the invention preferably have a pH of 7 to 8. In some cases, it may be necessary to use an additive, for example citric acid, to reduce alkalinity. Typically, the amount of additives to adjust the pH is 0.1 to 1% by weight of the binder.

Other, frequently present additives in the binding compositions are preservatives, wetting agents, antifoams and emollients. If present, these components are also used in minute amounts of about 0.05 to about 1% by weight of the composition prior to the addition of water.

When a lightweight ready-mixed binder composition is desired, ease can be achieved by incorporating specially treated expanded perlite into the formulation, according to U.S. Patent 3,454,267. It is well known in the art that expanded perlite has a particle size passing through a mesh having a mesh diameter. 150 micrometers (100 mesh) to be incorporated into the joint compound. In the ready-mixed binder mixture, the expanded perlite is preferably treated to be water insensitive. There are several ways to make expanded perlite water-insensitive. One of them is described in U.S. Pat. No. 4,525,388. It is preferred to treat the expanded perlite with a silicone or silane compound, but other materials may also be used. Specially processed expanded perlite is commercially available, for example, as a product of Silbrico Corporation.

In order to achieve the desired ease, the expanded perlite present should be present in an amount of at least about 3% of all ingredients to the ready-mixed binder before the addition of water. It is particularly preferred that the treated expanded perlite additive is at least about 5 to about 10% of the total additive to the ready mixed binder before the addition of water.

The ready-mixed cementitious composition of the invention may function as a curing bonding compound upon activation by an accelerator which initiates solidification. The accelerator overcomes the effect of the phosphate retarding additive and allows the calcium sulfate hemihydrate to solidify. Suitable accelerating materials are compounds having cations with a higher log K than calcium. Table I is a list of a series of metal ions in the order of their log K values measured using diethylenetriaminepentaacetic acid as a chelating agent for calcium ions.

Table I

Table II

Metal ion Log K value ferric 28.60 mercurial 26.70 copper 21.03 nickel 20.21 Cobalt 19,00 cadmium 18.93 leaden 18.87 zinc 18.14 ferrous 16.66 aluminum 16,00 manganese 15,11 calcium 10.63

Several materials have been found to initiate the solidification of ready-mixed cementitious compositions that have been stabilized by a phosphate retarder. It has been found that zinc sulfate is an excellent material useful as the accelerator of the cementitious compositions of the invention. Some materials having a high log K value and qualifying as accelerators have detrimental effects on the accelerated mixture and are therefore not suitable. These detrimental effects may be low dimensional stability, lack of binding, moisture release and increased viscosity. Aluminum sulphate is an accelerator that is unsuitable for harmful effects when used in calcium carbonate containing acceleration formulations. Accelerators containing ferrous ions are also not recommended due to the solidification of the finished walls and ceilings when bonding mixtures containing such ions are used. It may be desirable to incorporate a pigment in the accelerator component to provide a visual initiator of uniformity of mixing of the accelerator with the ready-mixed cement mix. A preferred accelerator mixture is 95% zinc sulfate and 5% ferric red by weight.

It has also been found that when a ready-mixed cement mixture is used without an accelerator additive, it functions as a drying type bonding compound. In addition, the ready-mixed cementitious compositions of the invention are useful in a variety of applications including, but not limited to, jointing compositions for finishing joints between gypsum panels of dry walls, fire walls, decorative and cast plasters, molded plasters, gypsum mixes and foundations. plasters (including finishing cladding) when mixed with suitable additional additives.

When used as fire-fighting compositions, it is desirable to incorporate reinforcing fibers such as cellulose fibers. The reinforcing fibers are usually about 0.1 to about 5% by weight of the composition.

The ready-mixed cement mixtures according to the invention may contain the following components:

Component Quantity (in% by weight) of filler

calcium sulfate hemihydrate 20 to 90 calcium carbonate 0 to 75 binder latex emulsion 1 to 15 non-leveling agent (if required) attapulg clay 1 to 10 thickener (if required) cellulosic material 0.1 to 2 retarder phosphate compound 0.1 to 10 protective equipment 0.05 to 1 lightening additive (if required) processed expanded perlite 3 to 25 Water as needed

The ready-mixed cementitious mixture can be prepared by adding a mixture of filler materials, optionally lightening agents, thickeners, non-leveling agents, and a retarder to the mixer containing water, latex binder and preservatives. The mixture may be mixed until smooth and filled into plastic containers. For some binder compositions, especially those that do not contain a lightening component, it may be desirable to subject the composition to vacuum prior to filling into containers. Generally enough water is added to the mixture to achieve a final Brabender viscosity of 300-600 BU units as measured by a Brabender viscometer. The viscosity is measured at room temperature (approximately 25 ° C) using a torsion head of 250 cm / g at a spindle speed of 75 to 78 rpm.

In accordance with the requirement of Section 35 of U.S. Patent No. U.C.112, the following examples illustrate the best mode of practicing the invention as known by the author today. In these exemplary embodiments, a 32-channel Molytek Data Acquisition System Product is used to set the time. The Molytek detects temperature as a function of time. The time to maximum temperature increase is considered to be the setting of the Molytek compound. According to ASTM C474, shrinkage and crack test with a length of 3.175 mm are performed. The accelerator used in the examples has a composition of 95% zinc sulfate and 5% ferric red. Since it is known in the art of bonding compositions that solidification type compositions have good crack resistance and good shrinkage properties, these tests have not been performed with solidification type compositions.

The invention is illustrated, but not limited, by the following examples.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The ready-mixed, solidifying type lightweight joint compound is prepared using a suitable retarder, tetranium pyrophosphate (TSPP) and as a preferred zinc sulfate accelerator. The cement mixture is prepared as follows:

component number dry (a) calcium sulfate hemihydrate (G) 996.80 mass (%) 66.45 filler calcium carbonate 225.00 15,00 attapulgite clay 75,00 5.00 hydroxypropyl methylcellulose Thickener (Methocel 250S) 5.25 0.35 processed expanded perlite Silbrico 35-34 105.00 7.00 TSPP retarder 6.00 0.40 citric acid 1.50 0.10 binder polymer ethylene vinyl acetate (55% solids) (Elvace 40-716) 150.00 5.50 Dry matter fungicide (Fungitrol 158) 1.50 0.10 bactericide (Nuosept 91) 1.50 0.10 Water 800.00

The dry ingredients are added to a blender containing water, latex binder and preservatives. The final amount of water is 800 cm ³ to achieve a final Brabender viscosity of 500 BU (with spindle). The mixture is blended to a smooth state and then filled into plastic storage containers.

The mixture ages at room temperature. After 175 days the mixture did not solidify.

Part of the mixture is tested as a drying type fastener without accelerator. No crack appeared in the 3.175 mm crack test. In the shrinkage test, the shrinkage is 20.3%.

100 g of the mixture are tested as a setting type of binding compound with powdered zinc sulphate as accelerator. Add 2.5 g of the mixture accelerator to one part with solidification (Molytek) in 35 minutes, but the mixture is a bit difficult to mix with the accelerator. To a further 100 g portion of the accelerator mixture was added 1.5 g of accelerator mixture which solidified (Molytek) in 80 minutes and remained smooth and creamy during mixing with zinc sulfate.

Example 2

Another ready-mixed, solidification-type lightweight joint compound is prepared using zinc hexametaphosphate as a retarder and a preferred zinc sulfate accelerator. The ingredients and amounts are exactly the same as in Example 1 except that 6 g of zinc hexametaphosphate is used instead of the TSPP retarder. To achieve a final Brabender viscosity (with spindle) of 500 BU, a final amount of water of 815 cm ³ is used. The mixture is mixed until smooth and filled into plastic storage containers.

The mixture ages at room temperature and does not solidify after 175 days.

Part of the mixture is tested as a drying type fastener without accelerator. Only small cracks appeared in the 3.175 mm crack test. In the shrinkage test, the shrinkage is 22.3%.

Two 100 g batches of the mixture are tested as a setting type of binding compound with powdered zinc sulfate as an accelerator. 2.5 g of the accelerator mixture are added to one part with solidification (Molytek) in 57 minutes, but the mixture is somewhat difficult to mix with the accelerator. To a second 100 g portion of the accelerator mixture is added 1.5 g of an accelerator mixture that solidifies (Molytek) in 92 minutes, while the mixture is somewhat difficult to stir.

Example 3

The ready-mixed, solidified type lightweight joint compound is prepared using sodium tripolyphosphate as a retarder and as a preferred zinc sulfate accelerator. The components and amounts are exactly the same as in Examples 1 and 2, except that 6 g of sodium tripolyphosphate is used as a retarder. A final amount of water of 900 cm ³ is used to achieve a final Brabender viscosity (with spindle) of 325 BU. The mixture is mixed until smooth and filled into plastic storage containers.

The mixture ages at room temperature and does not solidify after 175 days.

Part of the mixture is tested as a drying type fastener without accelerator. Only small cracks appeared in the 3.175 mm crack test. In the shrinkage test, the shrinkage is 24.2%.

Two 100 g batches of the mixture are tested as a setting type of binding compound with powdered zinc sulfate as an accelerator. 2.5 g of the accelerator mixture are added in one portion with solidification (Molytek) in 64 minutes, but the mixture is somewhat difficult to mix with zinc sulfate. To a second 100 g portion of the accelerator mixture is added 1.5 g of an accelerator mixture that solidifies (Molytek) in 113 minutes, and the mixture remains smooth and creamy during mixing with zinc sulfate.

Example 4

The ready-mixed, solidifying type lightweight joint compound is prepared using potassium tripolyphosphate as a retarder and as a preferred zinc sulfate accelerator. The ingredients and the amounts are exactly the same as in Examples 1 to 3, except that 6 g of potassium tripolyphosphate is used as a retarder. To achieve a final Brabender viscosity (with spindle) of 480 BU, a final amount of water of 875 cm ^J is used. The mixture is mixed until smooth and filled into plastic storage containers.

The mixture ages at room temperature and does not solidify after 175 days.

Part of the mixture is tested as a drying type fastener without accelerator. In the 3.175 mm crack test, only fine cracks appeared. In the shrinkage test, the shrinkage is 23%.

Two 100 g batches of the mixture are tested as a setting type of binding compound with powdered zinc sulfate as an accelerator. 2.5 g of the accelerator mixture are added in one portion with solidification (Molytek) in 68 minutes, and the mixture remains smooth and creamy during mixing with zinc sulfate. To a second 100 g portion of the accelerator mixture is added 1.5 g of the accelerator mixture which solidifies (Molytek) again in 93 minutes with gentle mixing with the accelerator mixture.

Example 5

The ready-mixed, solidified type lightweight joint compound is prepared using monoammonium phosphate as a retarder and as a preferred zinc sulfate accelerator. The components and amounts are exactly the same as in Examples 1-4, except that 6 g of monoammonium phosphate is used as a retarder. A final amount of water of 800 cm ³ is used to achieve a final Brabender viscosity (with spindle) of 510 BU. The mixture is mixed until smooth and filled into plastic storage containers.

The mixture ages at room temperature and does not solidify after 175 days.

Part of the mixture is tested as a drying type fastener without accelerator. In the 3.175 mm crack test, only fine cracks appeared. In the shrinkage test, the shrinkage is 21.7%.

Two 100 g batches of the mixture are tested as a setting type of binding compound with powdered zinc sulfate as an accelerator. 2.5 g of the accelerator mixture are added in one portion with solidification (Molytek) in 34 minutes and the mixture is extremely heavy when mixed with zinc sulfate. To a second 100 g portion of the accelerator mixture is added 1.5 g of an accelerator mixture that solidifies (Molytek) in 37 minutes and the mixture is extremely heavy and sticky on mixing.

Example 6

Two ready-mixed, lightening-type jointing mixtures are prepared using tribasic calcium phosphate in one of the mixtures and dibasic calcium phosphate in the other of the mixtures as retarders. The components and amounts are exactly the same as in Examples 1 to 5, except that 6 g of calcium phosphate is used as a retardant in the mixtures. The total final amount of water used was 800 cm @ 2. Both mixtures solidified at room temperature in less than 16 hours and therefore the test was not continued.

Example 7

The ready-mixed, solidifying type lightweight joint compound is prepared using monobasic potassium phosphate as a retarder and as a preferred zinc sulfate accelerator. The components and amounts are exactly the same as in Examples 1 to 6 except that 6 g of monobasic potassium phosphate is used as a retarder. A final amount of water of 800 cm ³ is used to achieve a final Brabender viscosity (with spindle) of 485 BU. The mixture is mixed until smooth and filled into plastic storage containers.

The mixture ages at room temperature and does not solidify after 175 days.

Part of the mixture is tested as a drying type fastener without accelerator. During the 3.175 mm crack test, only fine cracks to fine cracks appeared. In the shrinkage test, the shrinkage is 20.6%.

Two 100 g batches of the mixture are tested as a setting type of binder mixture using powdered zinc sulfate as an accelerator. 2.5 g of the accelerator mixture are mixed with one part which solidifies (Molytek) in 32 minutes and is extremely heavy when mixed with zinc sulfate. To a second 100 g portion of the accelerator mixture is added 1.5 g of an accelerator mixture that solidifies (Molytek) in 35 minutes and the mixture is extremely heavy and sticky on mixing.

Example 8

A ready-mixed, lightweight curing type joint compound of the following components is prepared for the in-service test:

Raw material Quantity (g) (a) Calcium sulphate hemihydrate 305,80 filler Calcium carbonate68,00 Atapulgite clay22,70 Hydroxypropylmethylcellulose thickener 1.60 Processed expanded perlite (Silbrico 43-23) 39,00 Retarder TSPP1,80 Citric acid0,45 Binder Polymer ethylene vinyl acetate (55% solids) 45.4

Fungitrol 1580.45

Nuosept91 0.45 water 280.00

The raw materials are weighed separately and mixed with water in a horizontal shaft paddle mixer until a uniform dispersion. In this test, 190 liters of initial water is used and the remaining water is added periodically to achieve viscosity. 90 liters of water are added to the initial mixture, consuming a total of 280 liters of water. The Brabender viscosity of the final blend (spindle) is 260 BU. The final mixture is packaged in containers and does not solidify after storage for 12 months at room temperature.

100-gram samples of the final blend were tested for solidification time (Molytek) prior to storage using various amounts of the zinc sulfate accelerator mixture. The results are as follows:

Accelerator Quantity (g)

2.5

2.0

1.5

1.0

Molyte solidification time (minutes) 39

After storage for several days, a portion of the composition is evaluated for performance as an unstable binder composition. The mixture still has a low viscosity (260 BU). After application with a 250 mm squeegee, the joint compound has a soft spread without any trouble.

Example 9

According to the following composition, a composition according to the invention suitable as a fire-fighting material is prepared.

Raw material Quantity (g) (a) Calcium sulphate hemihydrate 305,80 filler Calcium carbonate68,00 Atapulgite clay22,70 Binder Polymer ethylene vinyl acetate (55% solids) 45,35 Hydroxypropylmethylcellulose thickener 1,60 Citric acid0,45 Processed expanded perlite (Silbrico 35 -23) 31,78 cellulose fibers (Kayocel 6Bk50F) 3,62 retarder TSPP1,80

Nuosept 910.45

Fungitrol 1580.45 Water 246.00

This fire-fighting mixture complied with the fire test according to ASTME 814.

Example 10

The binder composition according to the invention is prepared according to the following composition:

Raw Material Quantity Dry

(G) mass (%) (B) calcium sulfate hemihydrate 987.80 65.85 filler calcium carbonate 225.00 15,00 attapulgite clay 75,00 5.00 hydroxypropyl methylcellulose thickener 5.25 0.35

processed expanded perlite

Silbrico 35-23 105.00 7.00 TSPP retarder 15,00 1.00 citric acid 1.50 0.10 binder polymer ethylene-vinyl- acetate (55% solids) 150.00 5.50 fungicide (Fungitrol 158) 1.50 0.10 bactericide (Nuosept 91) 1.50 0.10

The dry ingredients of the list are placed in a mixer containing water, a polymeric binder, a fungicide and a bactericide. The final amount of water is 960 cirP to achieve a final Brabender viscosity (with spindle) of 460. The mixture is mixed until smooth and filled into plastic storage containers. After 4 weeks the mixture did not solidify.

Part of the blends are tested as a drying type fastener without accelerator. The mixture has a wet density of 1.266 kg / l. In the 3.175 mm crack test only traces of fine cracks appeared. In the shrinkage test, the shrinkage is 19.1%. The utility properties are a bit difficult with a scattered dry trace, but they are easy to shape and create good edges.

Two 100 g batches of the mixture are tested as a setting type of binder mixture using powdered zinc sulfate as an accelerator. 2 g of the accelerator mixture are added in one portion with solidification (Molytek) in 37 minutes and the mixture is somewhat difficult to stir. To a second 100 g portion of the accelerator mixture is added 1 g of accelerator mixture which solidifies (Molytek) in 83 minutes and the mixture remains soft while mixing with zinc sulfate.

Example 11

Prepare a standard density binder mixture (not lightened) using the following composition:

raw material number dry mass (G) (%) (a) calcium sulfate hemihydrate 1268 63.45 filler calcium carbonate 300 15,00 mica 200 10.00 attapulgite clay 100 5.00 hydroxypropyl methylcellulose thickener 7 0.35 TSPP retarder 8 0.40 citric acid 2 0.10 binder polymer ethylene vinyl acetate (55% solids) 200 5.50 fungicide (Fungitrol 158) 2 0.10 bactericide (Nuosept 91) 2 0.10

The dry ingredients of the list are placed in a mixer containing water, a polymeric binder, a fungicide and a bactericide. The final amount of water is 900 cnp to achieve a final Brabender viscosity (with spindle) of 530. The mixture is blended until smooth and filled into plastic storage containers. After 4 weeks the mixture did not solidify.

Part of the mixture is tested as a drying type fastener without accelerator. The mixture has a wet density of 1.58 kg / l. In the 3.175 mm crack test, slight cracks and tears appeared. In the shrinkage test, the shrinkage is 25.9%. When applied to the joints of wall panels ensures a soft buttery spread.

Three 100 g batches of the mixture are tested as a setting type of binder mixture using powdered zinc sulfate as an accelerator. 2 g of the accelerator mixture are added in one portion with solidification (Molytek) in 67 minutes, but the mixture is somewhat difficult to stir. To a second 100 g portion of the accelerator mixture is added 1.5 g of the accelerator mixture which solidifies (Molytek) in 99 minutes and the mixture remains soft with stirring. To the third 100 grams portion was added 1 g of the accelerator mixture, which solidified (Molytek) in 181 minutes, and also this mixture remained soft with stirring.

Industrial usability

A cementitious composition that is relatively stable in a premixed state (i.e., premixed with water) and which can solidify and harden upon introduction of the accelerator into the composition. The ready-to-use cementitious cementitious compositions according to the invention are useful, for example, as joints for finishing joints between drywall gypsum panels, such as fire protection, decorative and cast plasters, grout and primer coatings and finishing plasters (including cladding). If the finished cement mixture is prepared as a joint compound, it can also be used as a drying compound without the addition of an accelerator.

Claims (11)

PATENT CLAIMS A finished cementitious composition comprising calcium sulfate hemihydrate as a filler and calcium dehydrated phosphate, binder and water as a retardant. The finished cement composition according to claim 1, characterized in that it contains calcium sulfate hemihydrate as filler, in an amount of 20 to 99% by weight, based on the anhydrous composition as a whole. The finished cement composition of claim 1, wherein the calcium sulfate hemihydrate is in α-crystalline form. The finished cementitious composition of claim 1, wherein the calcium sulfate hemihydrate is in β-crystalline form. The finished cement composition of claim 3, wherein the calcium-free phosphate retardant is selected from the group consisting of zinc hexametaphosphate, potassium tripolyphosphate, tetranium pyrophosphate, sodium tripolyphosphate, ammonium phosphate and monobasic potassium phosphate. 6. The finished cement composition of claim 1, further comprising calcium carbonate as filler. The finished cement composition of claim 1, wherein the composition comprises a thickener. 8. The finished cement composition of claim 1, wherein the composition comprises expanded perlite treated with a water insensitive material to form a lightweight composition. 9. The ready-to-use cementitious composition according to claim 1, characterized in that it comprises from 0.01 to 5% by weight of reinforcing fibers, based on the anhydrous composition as a whole. 10. The ready-to-use cementitious composition according to claim 8, characterized in that it contains a calcium-free phosphate-retardant in an amount of 0.1 to 1% by weight, based on the anhydrous composition as a whole. 11. The ready-to-use cementitious composition according to claim 8, characterized in that it comprises a separately packaged accelerator component comprising a cationic component having a log K value greater than the log K calcium ions and which, when mixed with the ready cement composition, allows the cement composition to solidify.